Do a little re-reading and it will become easier to understand.
Read my lips!!!! No double wall needed for good wood burner. :-)
No secondary combustion in the BushBuddy stove.
No flammable gas coming through the top holes of the bushbuddy, just plain air.
No gasses flow downward through the grate and up the space between the two walls of the bushbuddy.
The stove that Magnus has shown is his creation and is of a style not wanted by the average everyday backpacker wishing to burn twigs. His type of stove will work well with wood pellets and super dry wood shavings. Magnus admits that his type of stove is more finicky than a lot of alcohol stoves. My experience with his type of stove is exactly the same as what he experiences. They are a Pain In The Arse. They are not user friendly. They are a unique experience to build and play with. I suggest everyone to at least try one out as a DIY project.
Corey, your Ikea stove is a classic DIY easy stove to make. Stainless steel, rugged as all getout. A great choice of product to begin with for a stove.